The present invention relates generally to tape speed control systems for tape recorders, and more particularly to a circuit for controlling the speeds of two capstans of a cassette tape recorder of the dual capstan type so that the recording tape is transported under appropriately taut condition.
In conventional dual capstan type cassette tape recorders, the capstans are respectively located adjacent takeup and supply reels. To each of the capstans is coupled a wheel around which is supported a rubber belt so that the capstans are coupled together for unitary rotation by a single motor connected to the capstan located on the takeup reel side. A tape recorder of this type utilizes the elasticity of the rubber belt to rotate the supply-reel side capstan with a slip friction so that the latter is driven at a speed approximately 0.1% to 0.2% lower than the speed of rotation of the takeup-reel side capstan to maintain the recording tape between the capstans under taut condition.
However, the physical properties of the rubber belt tend to vary with time. Due to the delicate adjustment needed to maintain the specified speed relationship, conventional dual capstan tape recorders are not satisfactory for long use.